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right and surround channels to be lowered. This increases the channel separation achievable to around 30 decibels between channels. By careful tuning of the response of the amplifiers, the total amount of signal energy remains constant and is unaffected by the operation of the channel steering. Additionally, the response time of the system to changes in sound direction is important as too fast a response results in a twitchy feel, while too slow a response leaves sounds coming from an inappropriate direction.
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628:. DPL II processes any high-quality stereo signal source into five separate full frequency channels (right front, center, left front, right rear and left rear), while also decoding five channels from stereo signals encoded in traditional four-channel Dolby Surround. DPL II implements greatly enhanced steering compared to DPL, and as a result, offers an exceptionally stable sound field that simulates five-channel surround sound.
401:. It was capable of decoding Dolby Stereo four-channel soundtracks to three output channels (Left, Right, Surround). The Center channel was fed equally to the Left and Right speakers. The Surround channel was limited to a 100 Hz to 7 kHz frequency bandwidth, as dialog from the center channel could leak into the surround channel—there was as little as 3 dB of separation between LCR and Surround channels.
283:
Although Dolby
Surround was introduced as an analog format, all Dolby Digital decoders incorporate a digitally implemented Dolby Surround Pro Logic decoder for digital stereo signals that carry matrix-encoded Dolby Surround. One of the first was the MSP400 surround sound receiver and amplifier by RCA
631:
Because of the limited nature of the original Dolby Pro Logic encoding, many consumer electronics manufacturers introduced their own processing circuitry, such as the "Jazz", "Hall", and "Stadium" modes found on most common home audio receivers. DPL II forgoes this type of processing and replaces it
509:
A Pro Logic decoder also uses 'Steering Logic', which drives amplifiers to raise or lower the output volume of each channel based on the current dominant sound direction. For example, while a mono signal is played, the strong correlation to the center channel triggers the output volume of the left,
238:
and an adjustable delay, for improved channel separation and to prevent dialog leaking and arriving to listeners' ears first. The front center channel was equally split between the left and right channels for phantom center reproduction. This differed from the Cinema Dolby Stereo system which used
521:
Dolby
Surround and Dolby Pro Logic decoders are similar in principle, as both use matrix technology to extract extra channels from Dolby Stereo stereo-encoded audio. The terms Dolby Stereo, Dolby Surround and Lt/Rt are all used to describe soundtracks that are matrix-encoded using this technique.
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above the front left and right speakers, expanding a 5.1 or 7.1 system to 7.1 Height or 9.1. It identifies spatial cues in low-level, uncorrelated information, such as ambience and effects like rain or wind in the side and rear surround channels, and directs it to the front height speakers. The
242:
Later on in 1987, the Pro Logic decoding system was released to consumers. It featured virtually the same type of four-channel decoding as the Dolby Stereo theater processor with active steering logic and much better channel separation (up to 30 dB) as well as including a dedicated center
243:
channel output for the first time. Many standalone Pro Logic decoders also included a phantom center option for compatibility with earlier non-Pro Logic Dolby
Surround equipped home theaters to split the center channel signal to the L/R speakers for legacy phantom center reproduction.
640:) circuits used to derive five channels. The extra channel content is extracted using the difference between the spatial audio content between two individual channels of stereo tracks or Dolby Digital encoded 5.1 channel tracks and outputs it appropriately.
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In addition to 5 dB of noise reduction, the surround channel is slightly delayed, so that any front channel sounds that leak into the surround channel arrive at the listener after the front channels. This takes advantage of the
643:
In addition to five full-range playback channels, Pro Logic II introduced a Music mode that includes optimized channel delays and adds user controls to—for example—adjust apparent sound stage width.
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theater system on a 35mm optical stereo print and decoded back to the original 4.0 Surround. The same four-channel encoded stereo track was largely left unchanged and made available to consumers as
269:
to the left channel and a −90-degree phase shift to the right channel). The surround channel was often used for ambient background sounds in the original recording, music scores and effects.
257:(two-channel) soundtrack. The center channel is reduced in level by 3 dB and summed to the left and right channels; the surround channel is attenuated by 3 dB, passes through a
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system, available since 2003, can take two-channel stereo, Dolby
Surround (sometimes called Dolby Stereo Surround) and Dolby Digital 5.1 source material and up-convert it to 6.1 or
1127:
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is the earliest consumer version of Dolby's surround sound decoding technology. It was introduced to the public in 1982 during the time home video recording formats (such as
518:—audio that is present in the front speakers but delayed in the surround speakers will have the psychoacoustic effect of emanating from the front of the sound stage.
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capability. The name Dolby
Surround described the consumer passive matrix decoding technology; the professional, active-matrix cinema technology bore the name
1005:
Dolby
Digital (AC3) compatible hardware (DVDs, TVs, Blu-ray players) downmixes the 5.1 channel tracks into Lt/Rt stereo compatible with Pro Logic decoders
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is the full name that refers to the matrix surround format and decoding system in one. When a Dolby
Surround soundtrack is created in post-production (
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on home video. However, the original Dolby
Surround decoders in 1982 were a simple passive matrix three-channel decoder: L/R and mono
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noise reduction and is encoded on the left and right channels with opposite polarity (this is achieved by applying a +90-degree
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are capable of downmixing Dolby
Digital AC-3 5.1 to Lt/Rt stereo tracks compatible with Dolby Pro Logic I & II decoders.
17:
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is a complete replacement for Pro Logic that upmixes stereo and multi-channel inputs to play over Atmos configurations.
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decoder library for AC3 and A52 digital sound optionally exports Lt/Rt stereo sound compatible with Pro Logic decoders.
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SurCode for Dolby Pro Logic II is a Dolby-certified software encoder and decoder available in plug-in formats for
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A Dolby Pro Logic decoder/processor "unfolds" the soundtrack back into its original 4.0 surround—left and right,
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active steering and other processing to decode a center channel for dialog and center focused on screen action.
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A Pro Logic decoder/processor "unfolds" the sound into the original 4.0 surround—left and right,
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was the professional system that encoded four channels of film sound into two. This track used by the
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280:) mono rear channel—while systems lacking the decoder play back the audio as standard stereo.
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terminology in 2014. The term now refers to a new upmixer whose purpose is to enable
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expands on Pro Logic IIx with the addition of a height component, creating front
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receivers and speaker configurations to serve non-Atmos signals.
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Pro Logic II systems also have a mode designed specifically for
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234:. The surround channel was limited to 7 kHz. It also had
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sound systems. The format was adapted for home use in 1982 as
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1128:"Dolby Surround Pro Logic Decoder – Principles of Operation"
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Surround sound processing technology developed by Dolby Labs
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Older logo, before Dolby updated their overall logo design.
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In 1987 the decoding technology was updated and renamed
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Home theatre focus' history of dolby surround decoders
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as an alternative to digital surround formats such as
30:"Pro Logic" redirects here. Not to be confused with
1227:"Tech Blog – TV/DVD Surround Encoding Technologies"
502:, and a single limited frequency-range (7 kHz
276:, and a single limited frequency-range (7 kHz
211:were introduced. It was further improved with the
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38:Dolby Surround/Dolby Pro Logic/Dolby Pro Logic II
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149:, designed to decode soundtracks encoded with
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866:channels it adds are matrixed, not discrete.
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1065:Cohen, Simon; Hall, Parker (2023-11-10).
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1016:Dolby encoding and decoding matrices
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145:processing technology developed by
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1094:"Surround Sound Explained: Part 2"
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1485:Audiovisual introductions in 1986
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1092:Robjohns, Hugh (September 2001).
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1165:Scarpelli, Paul (2015-03-03).
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969:Software encoding and decoding
393:) were introducing Stereo and
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650:which is used in games for
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620:In 2000, Dolby introduced
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1194:"Dolby Pro Logic IIz"
870:Dolby Surround (2014)
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506:) mono rear channel.
236:Dolby Noise Reduction
193:stereo variable-area
1206:on January 22, 2009
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1146:on March 26, 2014
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1369:Dolby Stereo
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1329:Dolby Cinema
1234:. Retrieved
1230:
1220:
1208:. Retrieved
1204:the original
1197:
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1176:. Retrieved
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1148:. Retrieved
1141:the original
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922:Dolby Stereo
880:Product type
858:
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833:Dolby Stereo
791:Product type
761:
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735:Dolby Stereo
693:Product type
645:
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632:with simple
630:
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587:Dolby Stereo
545:Product type
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466:Dolby Stereo
424:Product type
399:Dolby Stereo
382:
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357:Dolby Stereo
315:Product type
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177:Dolby Stereo
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156:Dolby Stereo
154:
153:. The terms
150:
138:
137:
109:Dolby Stereo
43:Product type
1399:Doremi Labs
1389:Dolby Voice
1314:Dolby Atmos
1210:January 22,
1172:Audioholics
1150:February 8,
1039:AV receiver
1026:Dolby Atmos
957:Dolby Atmos
926:Dolby Atmos
648:video games
626:Jim Fosgate
516:Haas effect
267:phase shift
171:Right Total
1464:Categories
1417:CinePlayer
1412:CineExport
1105:2024-01-06
1078:2024-01-06
1050:References
906:Introduced
817:Introduced
719:Introduced
571:Introduced
450:Introduced
341:Introduced
167:Left Total
69:Introduced
1433:Ray Dolby
1407:CineAsset
1178:March 17,
982:HandBrake
935:Worldwide
842:Worldwide
744:Worldwide
596:Worldwide
475:Worldwide
366:Worldwide
189:Dolby SVA
122:Worldwide
32:Logic Pro
1364:Dolby SR
1324:Dolby 3D
1319:Dialnorm
1231:Neyrinck
1010:See also
656:GameCube
286:Dimensia
232:Surround
181:Dolby MP
1344:Dolby E
940:Website
932:Markets
898:Country
847:Website
839:Markets
809:Country
749:Website
741:Markets
711:Country
601:Website
593:Markets
563:Country
480:Website
472:Markets
442:Country
387:Betamax
371:Website
363:Markets
333:Country
263:Dolby B
127:Website
119:Markets
61:Country
1426:People
986:FFmpeg
976:liba52
658:, and
500:center
274:center
255:stereo
197:cinema
1442:Other
1144:(PDF)
1131:(PDF)
1034:Neo:6
888:Owner
799:Owner
701:Owner
634:servo
553:Owner
432:Owner
323:Owner
203:when
187:) or
141:is a
51:Owner
1238:2017
1212:2009
1180:2017
1152:2019
993:DAWs
984:and
974:The
909:2014
820:2009
760:The
722:2003
574:2000
453:1987
395:HiFi
389:and
344:1982
218:The
209:VCRs
205:HiFi
162:LtRt
159:and
113:LtRt
72:1982
1031:DTS
668:DTS
666:or
660:Wii
391:VHS
1466::
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768:.
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169:,
1292:e
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